Method for exchanging homologous DNA sequences in a cell using polyoma encapsulated DNA fragments

Abstract

A method for altering a cell by exchanging a preselected cellular DNA sequence with an exogenous DNA sequence different from the cellular DNA sequence employs an exogenous DNA sequence encapsidated in a polyoma or polyoma-like capsid. The polyoma capsid is then contacted to the cell so that the exogenous DNA sequence is introduced within the cell and exchanges with the preselected cellular DNA sequence by homologous recombination. A preferred article of manufacture comprises a polyoma capsid and a plurality of DNA sequences encapsulated within the polyoma capsid. The DNA sequences each comprise not more than an incomplete portion of a single preselected gene. The exogenous DNA sequence may optionally be complexed to a DNA binding protein, such as a recA protein, prior to encapsulating the exogenous DNA sequence within a viral capsid, so that the uptake of the DNA sequence into the capsid is enhanced.

That which is claimed is: 
     
       1. A method of altering, by homologous recombination, a preselected chromosomal DNA sequence encoding a protein in a polyoma-permissive cell, said method comprising the steps of: (a) providing a polyoma capsid having at least one single-stranded exogenous DNA sequence encapsulated therein,   said exogenous DNA sequence consisting essentially of a DNA sequence sufficiently homologous to said preselected chromosomal DNA sequence and of a length suitable to anneal to the complement of said homologous DNA sequence, and   (b) contacting said polyoma capsid to said polyoma-permissive cell so that said exogenous DNA sequence is introduced within said cell, anneals to the complement of said homologous DNA sequence, and exchanges with said chromosomal DNA sequence by homologous recombination.   
     
     
       2. A method according to claim 1, wherein said chromosomal DNA sequence comprises an incomplete portion of an endogenous structural gene in said cell, and wherein said exogenous DNA sequence is a fragment of said gene. 
     
     
       3. A method according to claim 1, wherein said polyoma-permissive cell is a mammalian cell. 
     
     
       4. A method according to claim 1, wherein said viral capsid has more than one of said exogenous DNA sequence encapsulated therein. 
     
     
       5. A method according to claim 1, wherein said exogenous DNA sequence is from about 50 to about 5,000 nucleotides in length. 
     
     
       6. A method according to claim 1, wherein said exogenous DNA sequence is single-stranded. 
     
     
       7. A method according to claim 6, wherein said exogenous DNA sequence has recA protein complexed thereto. 
     
     
       8. A method according to claim 1, wherein said exogenous DNA sequence is double-stranded, said double-stranded DNA sequence having protruding ends. 
     
     
       9. A method according to claim 8, wherein said protruding ends are modified to prevent the polymerization of said double-stranded DNA segment with a like DNA segment. 
     
     
       10. An article of manufacture useful for altering by homologous recombination a preselected chromosomal DNA sequence encoding a protein in a polyoma-permissive cell, said article comprising a polyoma viral capsid and at least one exogenous DNA sequence encapsulated within said polyoma viral capsid, said exogenous DNA sequence being sufficiently homologous to a strand of said preselected chromosomal DNA sequence to anneal to the complement thereof. 
     
     
       11. An article of manufacture as claimed in claim 10, wherein said exogenous DNA sequence consists of a fragment of said preselected chromosomal DNA sequence. 
     
     
       12. An article of manufacture as claimed in claim 10, wherein more than one of said exogenous DNA sequence is encapsulated within said polyoma viral capsid. 
     
     
       13. An article of manufacture as claimed in claim 10, wherein said DNA sequence is from about 50 to about 5,000 nucleotides in length. 
     
     
       14. An article of manufacture as claimed in claim 10, wherein said DNA sequence comprises a single-stranded DNA sequence. 
     
     
       15. An article of manufacture as claimed in claim 10, wherein said DNA sequence has RecA complexed thereto. 
     
     
       16. An article of manufacture as claimed in claim 10, wherein said DNA sequence is double-stranded, said double-stranded DNA sequence having protruding ends. 
     
     
       17. An article of manufacture as claimed in claim 16, wherein said protruding ends are modified to prevent the polymerization of said double-stranded DNA segment with a like DNA segment. 
     
     
       18. An article of manufacture useful for altering by homologous recombination a preselected chromosomal DNA sequence encoding a protein in a polyoma-permissive cell, said article comprising a polyoma capsid and at least one DNA sequence encapsulated within said polyoma capsid, said DNA sequence comprising not more than an incomplete portion of said chromosomal DNA sequence and having a length of from about 100 to about 300 nucleotides.